Aluminum salts as curing accelerators for aminoplast resins



3,084,071 ALUMENUM SALTS AS tIUidNG ACCELEPATURS AMTNQPLAST RESHNS William 3. Van Loo, in, Middlesex, Edgar E. Lineken,

Somerviiie, and Samuel J. GBrien, Duneilen, N.l., assignors to American Cyanamiti Qonipany, New York, NFL, a corporation of Maine Ne Drawing. Filed lune 11, 1959, Ser. No. 819,565 3 Claims. (Cl. 117-143) This invention relates to the use of aluminum salts of strong acids as curing catalysts or accelerators for thermosetting aminoplast textile finishing resins, and more particularly, it relates to the use of such salts in processes for finishing cellulosic textile materials with thermosetting aminoplast resins whereby acceptable and in some instances high wrinkle recovery may be obtained, without excessive losses in textile strength in the material so finished. Further, the invention relates to the cellulosic textile materials finished in accordance with the process of this invention.

Various catalysts and accelerators have been employed heretofore in the curing of thermosetting aminoplast resins in the finishing of cellulosic textile materials. Included among such catalysts are various metal salts including the strong inorganic acid salts of such metals as zinc, magnesium, and the like. To some extent, aluminum salts have been suggested as curing catalysts and accelerators for such resins.

Normally, in accordance with the prior art, the use of such accelerators involves their use in substantial amounts and curing is effected at temperatures ranging from about 275 F. to as much as 450 F. and more. In most instances, and as a practical matter, curing is usually effected at temperatures of from between about 300 and about 350 P. for periods of time from between about 3 minutes to about 1 /2 minutes, respectively.

in general, such procedures result in wrinkle recovery values for 80 x 80 cotton percale anywhere on the order of from between about 225 to about 260 as measured on a Monsanto wrinkle recovery tester. However, the tensile strength of the materials so finished is lower than normally desired, usually being from about 20 to about 60 pounds as measured on a Scott tester, where an untreated value of 100 or more is usual. In this connection, it has been recognized that as crease resistance increases, tensile strength losses also increase. Thus, in general, textile finishers of necessity are required to balance wrinkle recovery and tensile strength requirements.

As will be readily apparent, the impartation of wrinkle resistance to cellulosic textile materials as described gen erally above, can only be carried out in textile finishing mills having the necessary equipment to effect the rapid cure normally sought. Accordingly, the impartation of wrinkle resistance to cellulosic textile materials without such processing equipment is substantially unknown.

Accordingly, it is an object of the present invention to provide a process for finishing cellulosic textile materials whereby acceptable wrinkle recovery, i.e., a minimum of about 200 by the Monsanto crease angle tester, may be obtained with minimum losses in tensile strength.

it is a further object of the present invention to provide a process for obtaining acceptable and even a high order of wrinkle recovery, i.e., values in excess of 240 and a high order of tensile strength on cellulosic textile materials in which lower than normal amounts of catalysts are employed.

It is a further object of the present invention to provide a process for imparting acceptable to high wrinkle recovery without excessive loss of tensile strength in cellulosic materials, which process is carried out at considerably lower temperatures than those normally employed,

3,084,071 ?atenteel Apr. 2, i953 while a particular and preferred object of the present invention relates to a process for imparting wrinkle recovery to cellulosic textiles while producing minimum loss in tensile strength, which may be carried out at room temperatures.

It is a still further object of the present invention to provide a process for finishing cellulosic textile materials in which acceptable to high wrinkle recovery may be obtained without excessive loss in tensile strength, which does not entail the use of high speed curing apparatus normally associated with textile finishing.

According to the present invention, a process is provided for treating a cellulosic textile material which comprises applying thereto a water-soluble thermosetting aminoplast resin and a water-soluble aluminum salt of inorganic acid, so as to apply from between about 1 and 25% of said resin, based on the weight of the material, and from between about 1 and about 18% of said catalyst, based on the weight of the resin, and thereafter curing the resin to a water-insoluble state at a temperature between about room temperature and 250 F.

By cellulosic textile material as that term is employed herein, it is meant formed textile fabrics whether they be knitted, Woven, felted or otherwise formed, composed of at least 50% cellulose fibers, such as those composed of cotton, viscose rayon, jute, ramie, hemp, and the like. Preferably, the cellulosic textile materials consist substantially completely of cellulosic fibers, and more specifically cotton fibers. However, blends of such fibers with non-cellulose materials as for example wool, various synthetic fibers, as for example, polyester fibers, such as are sold under the trademark Dacron, nylon, acrylic fibers, such as those sold under the trademark of Creslan, Acrilan, Orlon and the like are contemplated.

The thermosetting aminoplast resins contemplated for use in accordance with the present invention are those thermosetting aminoplast resins normally employed to impart wrinkle resistance by the textile finishing industry. Thus, for example, the urea-formaldehyde resins including the methylol ureas and alkyl ethers, particularly methyl ethers of methylol ureas, the cyclic ureas, as for example, ethylene urea, 1,2-propylene urea, their formaldehyde condensates and alkylated (particularly methylated) derivatives, and the like. In addition, the polymethylol melamines and their alkylated derivatives, and more particularly their methylated derivatives are contemplated, wherein from 1 to 6 moles of formaldehyde are combined with the melamine and from 1 to 6 moles of an alcohol are also combined therewith. Thus, for example, dimethoxymethyl melamine, trimethoxymethyl melamine, tetramethoxymethyl melamine, hexamethoxymethyl melamine, and the like are contemplated. Still further, the guanarnine-formaldehyde condensates and their alkylated derivatives are contemplated, including various substituted guanamine-formaldehyde condensates and their alkylated, and in particular, their methylated derivatives. These resins are known to impart wrinkle resistance to cellulosic textile materials, and for use in accordance with the present invention, these materials may be employed singly or in combination with one another or in combination with other such resin the presence of which does not adversely afiect the process of this invention.

Of the aminoplast resins contemplated, those of the cyclic ureas, and in particular, the formaldehyde condensates of ethylene urea and 1,2-propylene urea are greatly preferred, and uniformly better results are obtained employing the same. Additionally, compositions containing substantial amounts of these preferred cyclic ureas are also generally preferred. By substantial amounts of these cyclic ureas, it is meant compositions or blends containing at least 20% by weight on a resin solids basis.

Thus, such compositions containing at least 20% of the cyclic ureas in combination with melamine-formaldehyde condensates, guanamine-formaldehyde condensates and the like are contemplated.

These aminoplast resins are water-soluble and essentially monomeric in form. While to some extent minor amounts of polymer may be present in these resins in the form of dimers, trimers, tetramers and the like, such presences do not adversely aifect the water solubility of these resins.

The aluminum salts suitable for use in accordance with the present invention are those aluminum salts derived from the strong inorganic acids, namely, nitric, hydrochloric and sulfuric. Thus, the salts employable are aluminum nitrate, aluminum chloride, and aluminum sulfate. Aluminum salts of weaker acids, and in particular organic acids, such as acetic, oxalic, glycolic and the like, are to some extent effective, though in general not suited for use in accordance with the present invention. Mixtures of two or more aluminum salts of the type contemplated for use in the present invention may be employed.

The water-soluble thermosetting aminoplast resins and the water-soluble salts of strong inorganic acids may be applied to the cellulose textile material by any of the means or techniques normally employed in crease proofing cellulosic textiles. Thus, for example, solutions containing these materials may be applied by spraying, dipping, submersion or by padding as that term is known and understood in the textile finishing art.

In applying the water-soluble thermosetting aminoplast resin and the aluminum salt accelerator therefor in accordance with the present invention, a minimum of about 1% up to about 25% of the thermosetting aminoplast resin should be applied to the cellulosic material, based on its dry weight. In addition, it has been determined that the amount 01'} the accelerator employable in order to achieve the effects of the present invention is between about 1 and 18%, based on the weight of resin solids employed. Preferably, the amount of resin solids applied to the textile material is between about 5 and and the amount of catalyst employed is between about 3 and thermosetting aminoplast resin to a water-insoluble state is eifected is between room temperature, about F., to about 160 F., there being a marked tendency for the wrinkle recovery and tensile strength and particularly the latter to be adversely affected at temperatures significantly in excess of about 150 F.

In order to illustrate the present invention, the fiollowing examples are given primarily by way of illustration. All parts and percentages contained therein are by weight unless otherwise specifically designated.

EXAMPLE 1 A series of pad baths were prepared containing 11.75% resin solids of dimethylol ethylene urea or a mixture of dimethylol ethylene urea in combination with a methylated methylol melamine employing varying amounts of aluminum nitrate or zinc nitrate as curing accelerators therefor, the amount of accelerator being expressed as a percent of the weight of the resin solids in the bath.

In all of the applications made, a 10% resin solids on the weight of the fabric were applied to x 80 cotton per-cale by padding, an wet pick-up being obtained. The fabrics were dried and cured at room temperature (70-80 F.) for a number of days. The fabrics were thereafter rinsed in cold water for 10 minutes and dried at room temperature.

The wrinkle recovery for the various treated materials was measured on a Monsanto wrinkle recovery tester following vthe tentative test method 664956 described on page 158 of the 1957 Technical Manual and Yearbook of the American Association of Textile Chemists and Colorists, volume 33. The tensile strength of the fabric was measured on a Scott tester, according to the A.S.T.M. standards. The wrinkle recovery values being reported in degrees and the tensile strength values being reported in pounds.

The amount of accelerator employed with the various resins and length of time of cure are recorded in Table I hereinbelow, as are the results of the evaluation respecting the wrinkle recovery and tensile strength of the materials so treated.

Table I 12% cat. 9% cat. 5% cat. 25% eat. 1% eat. Resin Catalyst Days cure W.R T.S. W.R. T.S. W.R T.S W'.R T.S. W.R T.S.

MMM-EU Al(N 0313.. 1 250 77 243 81 243 78 207 94 146 116 MMM-EIL. Al(NOa).-; 4 239 84 247 84 247 85 238 82 154 MMM-EU" Al(NOs)3- 9 230 82 240 79 264 75 236 80 147 113 M MM-EU. Al(NOa)a.. 16 223 88 232 84 241 80 250 83 204 94 MlVIM-EU- A1(NO3)3-- 25 218 86 226 87 235 80 248 83 167 101 MMM'EU Z11(NO3)2- 1 152 109 105 143 104 142 109 133 106 MMM-EU Z11(NOs)z 4 173 105 106 173 109 159 114 138 110 MMM-EU. Zn(NOa)z 9 184 93 172 97 165 102 168 109 154 116 MMM-EU Zl1(NO3)2 16 193 96 194 92 188 93 223 91 208 95 MMM-EU" Z11(NO3)z. 25 192 91 189 95 196 93 183 98 171 104 E A1(NOa)a 1 255 81 255 83 263 78 257 84 146 114 4 195 90 217 96 232 94 259 83 174 113 9 17.6 96 181 97 199 96 257 80 100 16 165 101 183 96 187 102 256 79 222 86 25 158 96 163 102 182 106 246 83 219 85 1 168 107 160 99 151 106 145 108 135 113 4 206 94 101 182 107 174 104 150 110 9 222 82 218 87 195 92 183 91 157 96 16 234 83 229 85 227 83 221 86 192 93 25 226 80 226 86 226 83 228 87 195 93 (Avg) 139 109 N0rE.-W.R.=Wrinkle recovery, total in degrees. T.S.=Tensile strength, pounds. MMM-EU= Methylated methylol melamine-dimethylol ethylene urea. EU=Dimethylol ethylene urea.

12%, expressed on the weight of the textile material dry, and the weight of the resin solids employed, respectively.

After the application of the resin solids and accelerator to the textile material, the resin finish is cured thereon to a water-insoluble state at a temperature of between about room temperature and about 250 F. It is a particular and preferred aspect of the present invention that curing may be efiected at relatively low temperatures and as will be seen in the examples hereinafter, excellent and remarkably good results are obtained at room tempera- .Table I hereinabove illustrates the good Wrinkle recovery without serious loss in tensile strength that can be obtained by curing .the thermosetting aminoplast resins identified at room temperature with an aluminum salt of a strong inorganic acid as the catalyst. The results further show that curing for too long a period of time will adversely affect the Wrinkle recovery and further that optimum curing time is dependent upon the amount of aluminum salt accelerator employed.

Still further, the results indicate that the results obture. Preferably, the temperature at which curing of the 75 tained with aluminum nitrate cannot be obtained with zinc nitrate under the same conditions of cure, and further that a comparison of these results with the results shown in Example 8 hereinafter illustrate that superior tensile strength is obtained by curing with aluminum nitrate at room temperature as compared with curing with zinc nitrate or magnesium chloride at high temperatures for the same degree of wrinkle recovery.

EXAMPLE 2 A series of pad bath-s were prepared containing 11.75% resin solids of either dimethylol ethylene urea or a resinous composition containing methylated methylol melamine and dimethylol ethylene urea and 12% of aluminum nitrate or zinc nitrate on the weight of the resin solids in the bath.

10% resin solids on the weight of the fabric were applied to 80x80 cotton percale by padding, and 85% wet pick-up being obtained. The fabric was dried and cured at room temperature (70-75 F.) for the number of days shown in Table 11 below and thereafter the fabrics were rinsed in cold water for 10 minutes and dried at room temperature.

The wrinkle recovery and tensile strength fabrics were measured as in Example 1. The result are shown in Table 11 below.

Table II 12% catalyst Resin Catalyst Days cure Wrinkle Tensile recovery, strength, degrees pounds EU A1(NO3)3.. 1 260 76 EU A1(NO3 a 4 259 77 EU A1(N()s)s. 9 228 83 EU Zn(NOa)z l 163 110 EU Zn(NO:s) 2.-. 4 186 93 EU Zn(NOa)z. 9 231 84 U Zn(NO3)z 16 244 79 MMM-EU. A1(NOt)a 1 263 79 MMM-EU. A1(NO3)a 4 252 MMM-E U. Al(NOs) s. 9 243 MMM-E U. Zn(NOs)-z. 1 161 102 MMM-EU... Zn(N0a)2 4 169 96 MMM-EU Zn(NO3)2 9 187 87 Untreated fabric. (Avg) 136 110 No'rn.EU-Di1nethylol ethylene urea. MMlVLEU-Methylated methylol melamine-dimethylol ethylene urea.

Table 11 illustrates the advantages aluminum nitrate gives as compared with Zinc nitrate, particularly with curing time of about one day.

EXAMPLE 3 A series of pad baths were prepared containing 11.75% resin solids of dimethylol ethylene urea or 11.75% resin solids of a mixed resinous composition containing a methylated methylol melamine and dimethylol ethylene urea and 12% of aluminum nitrate on the weight of resin solids in the baths. 7

19% resin solids on the weight of the fabric were applied to 80x 80 cotton percale by padding, an 85%, wet pick-up being obtained. The fabrics were dried and cured at room temperature (70-75 F.) for the number of hours indicated in Table Ill below. The fabrics were then rinsed in cold water for 10 minutes and dried at room temperature.

The results of this experiment are shown in Table III below.

Table III Wrinkle recovery, total in degrees Hours cure Resin EU Resin MMM-EU 2- 250 191 4 256 213 6. 261 219 8. 261 239 Untreated 154 Note.EU-Dimethylol ethylene urea. MMM-EUMethylated methylol melamine-dimethylol ethylene urea.

'tion with dimethylol ethylene urea.

hours or longer.

EXAMPLE 4 A series of pad baths were prepared containing 11.75 resin solids of a resinous mixture containing a methylated methylol melamine and dimethylol ethylene urea and 12% of aluminum nitrate as an accelerator, aluminum chloride or aluminum sulfate on the weight of the solids present in the bath.

10% resin solids on the weight of the fabric were applied to x 80 cotton percale by padding. The fabrics were dried and cured at room temperature (70-75 F.) for a 24-hour period. The fabrics were then rinsed in cold water for 10 minutes and dried at room temperature. The wrinkle recovery was measured as in Example 1 and the results are shown in Table IV.

Table IV Salt: Wrinkle recovery, degrees Aluminum nitrate 242 Aluminum chloride 228 Aluminum sulfate 234 Untreated 150 Table IV hereinabove illustrates that the aluminum salts contemplated by the present invention are about equally effective as catalysts for curing thermosetting aminoplast resins containing a methylated methylol melamine at room temperature.

EXAMPLE 5 A series of pad baths were prepared containing 11.75 8.82%, 5.88% and 2.94% resin solids of dimethylol ethylene urea or a resinous composition containing a mixture of a methylated methylol melamine in combina- These pad baths contained 12% of aluminum nitrate on the weight of the resin solids in the pad bath.

Employing these pad baths, 10%, 7.5%, 5% and 2.5% resin solids were applied to 80x80 cotton percale by padding and an wet pickup was obtained. The fabrics were dried and cured at room temperature (70- 75 F.) for 24 hours. The fabrics were then rinsed in cold water using a Bendix washer and dried at room temperature.

The wrinkle recovery was determined as in Example 1.

The results are shown below in Table V.

Note.-EU-Dimethylol ethylene urea. MMM-EU-Methylatcd methylol melamine-dimethylol ethylene urea.

EXAMPLE 6 A series of pad baths were prepared as in accordance,

with Example 5. Employing these pad baths, 10%, 7.5 5% and 2.5 resin solids were applied to 80 x 80 cotton percale by padding and an 85% wet pick-up was obtained. After drying for 24 hours at room temperature the fabrics were rinsed for 10 minutes in cold or hot water as indicated in Table VI and dried at room temperature. The Wrinkle recovery and tensile strength were determined as in Example 1. The results are shown below in Table VI.

Note.--EUDirnethylol ethylene urea. MMM-EU-Miethylated methylol melamine-dimethylol ethylene urea.

W.R.=Wrinkle recovery, total in degrees. T.S.=Tensile strength,

pounds.

Table VI above illustrates that there is no appreciable difference between rinsing the resin treated fabric after cure with either hot or cold water.

The results of Examples and 6 show that as the amount of the thermosetting aminoplast resins applied to the fabric is increased, the wrinkle recovery increases, and the tensile strength decreases.

EXAMPLE 7 A series .of .pad baths were prepared containing resin solids of the resins identified in Table VII below and 8 The results in Table VII show that a low temperature cure of 160 F., aminoplast resins may be effectively cured employing comparatively little catalyst to produce a high order of wrinkle recovery. Thus, with dimethylol 5 ethylene urea and mixtures of dimethylol ethylene urea and methylated methylol melamine between =3 and 6% of aluminum nitrate as the accelerator is superior or equal in function to 12% of zinc nitrate.

EXAMPLE 8 A series of pad baths were prepared containing 11.75% resin solids of dimethylol ethylene urea (EU), a dimethyl ether of trimethylol melamine (DTM), and a partially polymerized, substantially fully methylated dimethylol urea (UP), and as accelerators aluminum nitrate, zinc nitrate or magnesium chloride in the amount specified in Table VIII, expressed as percent on the weight of the resin solids in the bath.

10% resin solids on the weight of the fabric was applied to 80 x 80 cotton percale by padding and an 85% wet pick-up was obtained. The fabrics were dried and cured at 250 F. for 3 minutes, 290 -F. for 2 minutes or 350 F. for 1.5 minutes.

The wrinkle recovery and tensile strength of the fabric was determined as in Example 1. The results of this evaluation are shown in Table VIII below.

Table VIII Catalyst 250 F., 3min. 290 F., 2 min. 350 F.,1.5min.

Resin Per- Kind cent on W.R. T.S. W.R. T.S. W.R. T.S.

resin Al(NOs)s 12 233 58 247 48 256 41 9 227 67 244 53 261 43 6 236 69 241 59 257 3 251 84 257 83 261 67 1 152 105 172 102 198 85 12 258 76 258 70 264 69 12 242 257 65 258 76 12 232 81 233 86 252 74 9 228 237 81 250 74 6 226 85 237 83 251 83 3 199 85 205 87 240 81 1 151 110 154 109 179 04 12 216 87 226 86 240 77 gClz 12 176 94 213 00 246 74 AI(NO3)3 12 213 61 239 46 240 33 AKNOa): 9 226 64 235 49 2A7 38 AKNOz') 3.- 6 220 67 231 57 243 44 A1(N0a)a 3 229 83 226 80 253 64 (N03 1 146 113 157 111 165 Zl1(NO;4)z. 12 229 82 235 77 248 71 UF MgQlz- 12 158 101 197 95 228 80 Untreate 126 N0rE.W.R.Wrinkle recovery, total degrees. T.S.-Tesile strength, pounds.

the varying amounts of aluminum nitrate or zinc nitrate on the weight of the resin solids in the bath indicated in said table.

7.4% resin solids on the weight of the fabric were applied to 80 x 80 cotton percale by padding, a 74% wet pick-up being obtained. The fabrics were dried and cured at 160 F. for 8 minutes. The wrinkle recovery of the fabric was measured as in Example 1 and the results are shown in Table VII below.

Table VII Catalyst Wrinkle Resin recovery,

Kind Percent on degrees EU AKNOz): 3 270 Zn(NO;)2 12 273 MMM-EU AJ(NO3):.-.- 6 251 MMM-EU n(NO: 2... 12 238 HMMM A (NO3l; 3 256 IPU Al(N03)- 3 273 Untreated l Methylated methylol melamine-dirnethylol ethylene urea. 1 Highly methylatedsmethylol melamlne. 3 Dimethylol 1,2-propylene urea.

The results of Table VIII hercinabove show that the exemplary aminoplast resins may be cured at high temperatures with aluminum nitrate as a catalyst. Comparisons with Examples 1, 2 and 3 show that curing at high temperature causes a greater loss in tensile strength than curing at low temperatures for the same degree of wrinkle recovery.

The results further show that under these conditions of curing, a minimum amount of aluminum nitrate is about 3% on the weight of resin solids in the bath. Also, it demonstrates that 3% alminum nitrate gives approximately equal results to those obtained with 12% of other known curing accelerators such as zinc nitrate or magnesium chloride. The results further show that, in general, for a given amount of aluminum nitrate, the wrinkle recovery increases and the tensile strength decreases as the curing temperature is increased.

A review of the above experiments may lead to the conclusion that the low temperature curing efiiciency of the aluminum salts contemplated by the present invention is in effect due to the low pH of the pad bath, and as a consequence, the low pH of the curing medium. This has been demonstrated not to be the case by an experiment in which magnesium chloride and zinc nitrate catalysts were prepared in a pad bath and the pH adjusted to a value between 3.7 and 3.8, which corresponds to the pH of pad baths containing aluminum nitrate in accordance with the present invention. Such an adjustment in the pad baths of magnesium chloride and zinc nitrate do not render such pad baths containing either dimethylol ethylene urea or mixtures of dimethylol ethylene urea with methylated methylol melamine resins eifective as curing accelerators at room temperature, as are the aluminum salts of this invention. It is thus believed that the peculiar catalytic function of the aluminum salts of the present invention is not the function of pH.

While the present invention has been described primarily with respect to compositions containing thermosetting water soluble aminoplast resins and specific curing accelerators, other textile finishing resins and accelerators may be employed in combinations which do not significantly impede or restrict the activity of these components in accordance with this invention, as well as other textile finishing and treating agents and auxiliaries such as softeners, lubricants and the like.

We claim:

1. A process for treating cellulosic textile material which comprises applying thereto a water soluble thermosetting aminoplast resin and a water soluble aluminum salt selected from the group consisting of aluminum chloride, aluminum nitrate, and aluminum sulfate, so as to apply from between about 1% and 25% of said resin, based on the weight of the material, and from between about 1% and 18% of said salt based on the weight of the resin, and thereafter curing the resin to a water insoluble state at a temperature between about room temperature and F.

2. A process according to claim 1 in which the thermosetting aminoplast resin comprises dimethylol ethyleneurea.

3. A process for treating cellulosic textile material which comprises applying thereto from about 5 to 10% of dimethylol ethyleneurea and 3 to 12% of aluminum chloride, based on the weight of ethyleneurea, and thereafter curing the dimethylol ethyleneurea to a water insoluble state at a temperature of from about room temperature to 160 F.

References Cited in the file of this patent UNITED STATES PATENTS 2,339,203 Stiegler et al. Jan. 11, 1944 2,512,195 Bener June 20, 1950 2,898,238 Van Loo et al Aug. 4, 1959 

1. A PROCESS FOR TREATING CELLULOSIC TEXTILE MATERIAL WHICH COMPRISES APPLYING THERETO A WATER SOLUBLE THERMOSETTING AMINOPLAST RESIN AND A WATER SOLUBLE ALUMINIUM SALT SELECTED FROM THE GROUP CONSISTING OF ALUMINIUM CHLORIDE, ALUMINUM NITRATE, AND ALUMINUM SULFATE, SO AS TO APPLY FROM BETWEEN ABOUT 1% AND 25% OF SAID RESIN, BASED ON THE WEIGHT OF THE MATERIAL, AND FROM BETWEEN ABOUT 1% AND 18% OF SAID SALT BASED ON THE WEIGHT OF THE RESIN, AND THEREAFTER CURING THE RESIN TO A WATER INSOLUBLE STATE AT A TEMPERATURE BETWEEN ABOUT ROOM TEMPERATURE AND 160* F. 